[asterisk-users] PJSIP trunk is down when DNS was not available during the Asterisk start.

[Joshua C. Colp]

On Thu, Aug 27, 2020 at 8:58 AM Leonid Fainshtein <
leonid.fainshtein at xorcom.com> wrote:

> I see that pjsip_resolver.c tries unsuccessfuly to resolve the
> hostname each 10 seconds:
>
> [Aug 27 07:51:36] DEBUG[595] res_pjsip.c: 0x7f75282eb150: Wrapper created
> [Aug 27 07:51:36] DEBUG[595] res_pjsip.c: 0x7f75282eb150: Set timer to
> 2000 msec
> [Aug 27 07:51:36] DEBUG[595] res_pjsip/pjsip_resolver.c: Performing SIP
> DNS resolution of target 'rpi6.in.xorcom.com'
> [Aug 27 07:51:36] DEBUG[595] res_pjsip/pjsip_resolver.c: Transport type
> for target 'rpi6.in.xorcom.com' is 'Unspecified'
> [Aug 27 07:51:36] DEBUG[595] res_pjsip/pjsip_resolver.c: [0x7f75282fe7f8]
> Created resolution tracking for target 'rpi6.in.xorcom.com'
> [Aug 27 07:51:36] DEBUG[595] res_pjsip/pjsip_resolver.c: [0x7f75282fe7f8]
> Added target 'rpi6.in.xorcom.com' with record type '35', transport
> 'Unspecified', and port '0'
> [Aug 27 07:51:36] DEBUG[595] res_pjsip/pjsip_resolver.c: [0x7f75282fe7f8]
> Added target '_sips._tcp.rpi6.in.xorcom.com' with record type '33',
> transport 'TLS', and port '5061'
> [Aug 27 07:51:36] DEBUG[595] res_pjsip/pjsip_resolver.c: [0x7f75282fe7f8]
> Added target '_sip._tcp.rpi6.in.xorcom.com' with record type '33',
> transport 'TCP', and port '5060'
> [Aug 27 07:51:36] DEBUG[595] res_pjsip/pjsip_resolver.c: [0x7f75282fe7f8]
> Added target '_sip._udp.rpi6.in.xorcom.com' with record type '33',
> transport 'UDP', and port '5060'
> [Aug 27 07:51:36] DEBUG[595] res_pjsip/pjsip_resolver.c: [0x7f75282fe7f8]
> Added target 'rpi6.in.xorcom.com' with record type '1', transport 'UDP',
> and port '5060'
> [Aug 27 07:51:36] DEBUG[595] res_pjsip/pjsip_resolver.c: [0x7f75282fe7f8]
> Starting initial resolution using parallel queries for target '
> rpi6.in.xorcom.com'
> [Aug 27 07:51:36] DEBUG[605] res_pjsip/pjsip_resolver.c: [0x7f75282fe7f8]
> All parallel queries completed
> [Aug 27 07:51:36] DEBUG[605] res_pjsip/pjsip_resolver.c: [0x7f75282fe7f8]
> Resolution completed - 0 viable targets
> [Aug 27 07:51:36] DEBUG[595] res_pjsip/pjsip_resolver.c: [0x7f75282fe7f8]
> Invoking user callback with '0' addresses
> [Aug 27 07:51:36] DEBUG[595] res_pjsip.c: 0x7f75282eb150: PJSIP tsx
> response received
> [Aug 27 07:51:36] DEBUG[595] res_pjsip.c: 0x7f75282eb150: Cancelling timer
> [Aug 27 07:51:36] DEBUG[595] res_pjsip.c: 0x7f75282eb150: Timer cancelled
> [Aug 27 07:51:36] DEBUG[595] res_pjsip.c: 0x7f75282eb150: Callbacks
> executed
> [Aug 27 07:51:36] DEBUG[595] res_pjsip.c: 0x7f75282eb150: wrapper
> destroyed
> [Aug 27 07:51:36] DEBUG[595] res_pjsip/pjsip_options.c: Contact g145/sip:
> rpi6.in.xorcom.com status didn't change: Unreachable, RTT: 0.000 msec
> [Aug 27 07:51:36] DEBUG[595] res_pjsip/pjsip_options.c: AOR 'g145' now has
> 0 available contacts
>
> But a DNS server is available at this time:
> # host rpi6.in.xorcom.com
> rpi6.in.xorcom.com has address 192.168.0.175
>
> # ping rpi6.in.xorcom.com
> PING rpi6.in.xorcom.com (192.168.0.175) 56(84) bytes of data.
> 64 bytes from rpi6.in.xorcom.com (192.168.0.175): icmp_seq=1 ttl=64
> time=0.990 ms
>

What DNS resolver implementation is in use? system or unbound?

Asterisk itself doesn't do any caching, we defer it to the underlying
implementation. It could be caching a negative response.

-- 
Joshua C. Colp
Asterisk Technical Lead
Sangoma Technologies
Check us out at www.sangoma.com and www.asterisk.org
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